Storage.com

flash memory card

By Kinza Yasar

What is a flash memory card?

A flash memory card -- sometimes called a storage card -- is a small storage device that uses non-volatile semiconductor memory to store data on portable or remote computing devices. Such data includes text, pictures, audio and video.

Most current products use flash memory, although other memory technologies are being developed, including devices that combine dynamic RAM (DRAM) with flash memory, such as UltraRAM, which is based on quantum memory and computing.

Evolution of the flash memory card

Earlier removable storage media -- such as the PC card, smart card and similar cards used for computer gaming systems -- are also considered memory cards. However, the newer types of memory cards are smaller, require less power, have higher storage capacities and are portable among more devices. Because of these features, memory cards are influencing the production of an increasing number of small, lightweight, low-power devices.

Memory cards offer several advantages over a hard disk drive (HDD): They're much smaller and lighter, are extremely portable, are silent, enable more immediate access and are less prone to mechanical damage. However, an HDD still offers a compelling advantage: Although flash prices are coming down, a typical memory card still costs more -- and has a lower storage capacity -- than a high-capacity HDD.

Types of memory card formats: Consumer devices

There are several flash memory card types on the market, roughly divided between consumer devices and enterprise storage devices. The cards come in varying sizes and storage capacities, typically corresponding directly to their price.

Popular memory card formats used in consumer devices include the following:

Most types of memory cards available have constantly powered, non-volatile memory, particularly NAND flash. Non-volatile memory safeguards data in the event of a power outage, software bug or other disruption and also eliminates the need to periodically refresh data on the memory card. Because memory cards use solid-state media, they have no moving parts and are less likely to suffer mechanical difficulties.

Consumer solid-state drive flash cards

Unlike SD memory cards, solid-state drives (SSDs) are nonremovable storage typically built into larger devices, such as servers and computers. Consumer-grade SSDs embed silicon-based memory chips as storage media for persistent storage of data.

The earliest SSDs were generally designed for consumer devices. The debut of the Apple iPod in 2005 marked the first notable flash-based device to broadly penetrate the consumer market. Today, SanDisk offers a line of extreme portable SSDs known as SanDisk Extreme that scale to 4 TB of flash capacity.

The earliest commercially designed SSDs were made with single-level cell (SLC) or multi-level cell (MLC) flash. SLC uses a high grade of flash media to provide performance and endurance, but it typically costs twice as much as MLC flash.

Some consumer-grade flash memory cards are used by companies to cache reads and writes with hybrid flash storage. Enterprise MLC is an MLC NAND variant with enhanced write cycles compared to consumer-grade MLC. Some newer enterprise SSDs use triple-level cell NAND flash, which stores 3 data bits per flash cell, and quad-level NAND (QLC NAND), which can store up to 4 bits of data per memory cell. SSDs made with QLC NAND represent the next evolution in flash memory products.

Enterprise-grade SSDs

In most respects, the above types of flash memory cards differ from those used in enterprise storage. SSDs aren't all created equally and, therefore, aren't suited for all applications. As such, the difference between a client SSD and an enterprise SSD is vast. For example, the low-cost, consumer-grade SSDs, such as Samsung Evo, WD Green from Western Digital and Seagate BarraCuda, are meant for consumer use cases, while the expensive enterprise-grade options, including Samsung PM883, Western Digital Ultrastar, Seagate Nytro and Kingston Technology DC500, are used in data centers and corporate environments.

EMC -- now Dell EMC -- is credited with being the first vendor to include SSDs in enterprise storage hardware when it added them to its Symmetrix disk arrays in 2008, spawning the advent of hybrid arrays that combine flash drives with a traditional spinning disk. Initially, enterprise SSDs in hybrid arrays were relegated to caching read data in flash due to their higher cost and lower endurance compared to HDDs.

SSDs are commonly available in form factors similar to traditional HDDs, such as 1.8-inch, 2.5-inch and 3.5-inch. SSDs can be inserted into slots in computer servers -- referred to as server-side flash storage -- or used as part of an enterprise flash storage array system.

PCIe-based SSDs are designed around Peripheral Component Interconnect Express (PCIe), a high-speed expansion card format that connects a computer with its attached peripherals. Compared to Serial Advance Technology Attachment (SATA) SSDs, PCIe SSDs are preferred but are costlier, due to their direct connection to a system's motherboard. They offer faster data transfer rates and are commonly used in devices that require high write/read speed data connections.

PCIe has a point-to-point architecture, enabling each device to connect to a host via its own serial link, rather than by sharing a network bus. By virtue of this direct connection, PCIe SSDs are generally rated to deliver higher performance than SATA, Serial-Attached SCSI (SAS) or Fibre Channel (FC) SSDs.

Flash memory cards in servers

Aside from SSDs, other form factors for server-based flash storage include the following:

Emerging flash memory card specifications

The non-volatile memory express (NVMe) protocol is a specification that enables an SSD to exploit the PCIe bus. NVMe operates at the host controller to define the command set and feature set needed to streamline the input/output stack. The goal is to enable PCIe-based SSDs to deliver low latency and higher throughput and consume less power when compared to SAS or SATA SSDs. The newest specification of NVME, NVMe 2.0c, was released in October 2022.

The nonprofit NVM Express Inc. developed the NVMe over Fabrics (NVMe-oF) industry specification to enable the NVMe storage interface to transfer data commands via Ethernet, FC, InfiniBand and other network fabrics. NVMe-oF is quickly becoming a popular storage networking protocol that offers high performance, low latency, scalability and support for existing network protocols, such as FC, TCP and remote direct memory access.

Hybrid RAM-flash memory and next-gen memory card technology

For decades, traditional memory technologies, including DRAM and NAND flash, have served as reliable memory technologies. However, with the explosive growth in data generation and consumption, these options are nearing their performance, capacity and energy efficiency limits. To overcome these constraints and unlock new possibilities, several next-generation memory technologies have emerged that have the power to meet the increasing needs of the data-focused world.

The following are a few next-generation flash memory offerings that are changing the way industries work by offering faster, better and more dependable memory options:

QLC flash is quickly gaining popularity as a viable memory storage technology. Explore its importance and influence on the hybrid cloud storage options available on the market.

18 Jul 2023

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